Electrical measuring instrument



ELECTRICAL MEASURING INSTRUMENT r n l Filed-Feb. 16, 1922 hm-SW 1 WITNESE INVENTOR 580/318 3007?. I BYY I beam , ATTORNEY A ug'. 1931. c5.SPEIRTI ELECTRICAL MEASURING INSTRUMENT Original iled Feb. 16, 71922 2Sheets-Sheet 2 v a: 3 7 :4 2 l6 r 1 i V/ o: /0 y 0,- 32 I ClocK Iflechamlm 51 :9 30 F n t F 11 I J r 1 l 1'11 I INVENTOR George S'pevhATTORNEY Patented Aug. 4, 1931' um'rao STATES PATENT orrica clonal:sm'rn, or covme romm'rucn. assmnoa, BY nnmc'r AND mnsnn Asa are rrownsmenousn ELECTRIC a umumc'runme comm, A con- POBATION OI PENNSYLVANIA.

murmur. moans ms'rmmmwr Original application fled Iebrury 18, 1988,Serial Io. 538,856. Divided and this application filed Kay 7,1854.Serial No. 711,688.

' My invention relates to electric meters and particularly to graphicdemand meters.

present application is a division of my application, Serial No. 536,956,filed February 16, 1922.

One object of my invention is to provide a meter that shall have meansfor measuring re active volt-ampere demand, wattdemand and the total orvolt-am re demand.

vide a meter that shall ave means, including a chart, for recording theavera power factor of a load over a predetermined demand interval. p :161 Referring to the accompanying drawin wherein I have illustratedconcrete embodiments of my invention,

Figure 1 is a plan view of a meter which embodies certain features ofthe invention; .0 and Fig. 2 is a similar view of a modificationthereof.

Fig. 3 is an elevational view of the meter shown in Fig. 1. 4

comprises two arms 1 and 2,-pivotally mounted at 3 and 4, respectively.The arm 1 is driven in an suitable manner by a reactive voltampereoursmeter as shown in.Fig. 3. The arm 2 is similarly driven by a watt-hourmeter 36. These meters are of-the usual integating demandtype, such asthat disclosed in atent No. 1,336,611,'issued April 13,1920, to'Bradshaw et al.

The detailed construction of such meters is disclosed in my priorapplication above referred to. The motor elements of the meters 35 and36 are geared to arms 1 and 2 to drive them at a rate proportional tothe power and reactive components of the load,respectively, for a.certain period of time. This period, which is termed the demandinterval, may be 15 minutes. At the end of this demand interval, thedriving connection between gears 37 and 28 and 29 and 30, respectively,is broken by the movement of the member 31 of the clock mechanism 32 andthe recording elements including the arms land 2 are permitted torestore to normal by the spring 15 so which is connected at one end tothe bracket Another object o minvention is to pro-- Referring to Figures1-and'3, the meter 33 by the pin 34. The specific construction of theseelements may be similar to that shown ment of the arms 1 and 2, and,therefore, in-

scribes a line upon the chart in accordance with the magnitude and werfactor of the load during each demand mterval. The chart 8 is providedwith semi-circular reference lines 9 drawn about theini'tial position ofthe stylus as a center. These lines may be marked in accordance with thecalibration of the meter to facilitate reading the volt-amperehourdemand of an time interval as'represented b the lengt of the lineinscribed by the stylus I A cord 10 is attached to thestylus7 and passesbetween two rollers 11 and thence around a drum 12 to which it issecured. The drum 12 is provided with a maximum demand pointer 13 thatcooperates with a suitable scale 14 to provide a temporary indication ofthe maximum volt-am ere demand of which a permanent record is obtainedupon the; chart. At the end of each demand interval, I

a spring 15 restores the drum 12, the links 5 and-6, and the arms 1 and2 to normal. The arms 1 and 2 are also provided with maximum demandpointers 16 and 17 to rovide an indication of the maximum reactive andpower component demands.

In Fig. 2 is shown a modification of the chart and recording mechanism.The arms 1 and 2 correspond to the same elements in Fig. 1 and cooperatein the same way to actuate a stylus upon a chart 8'. The chart 8 isprovided with power-factor lines 18, 19, 20 and 21. I

It will be obvious that, when the load is a unity power-factor load, thearm 1 remains stationary, and, therefore, the path of the stylus7'coincidcs with the line 18. The position of the stylus 7 at the end ofthe demand period upon this line indicates an average power factor ofduring the demand i nterval. From similar considerations, it will beapparent that the line 19 represents a load the average power factor ofwhich is zero.

In the event that the average power factor of the load is between thesetwo values, the stylus 7 will reach a position intermediate the twolines 18 and 19. Thus, if the power factor is 70.7% lagging, thereactive component and power component elements 1 and 2 will be drivenat the same rate of speed and the stylus 7 will move along the line 20.The location of the stylus 7 upon the line 20 at the end of the demandinterval will indicate, therefore, that the average power factor of theload for the interval was 7 0.7 In the same way, for 70.7% power factorleading, the reactive component element 1 will be driven in the reversedirection and the stylus 7 will travel along the line 21.

A pinion 22 of the clock mechanism for timing the. demand period carriesa pin 23 that is periodically actuated just before the stylus 7 isreturned to normal. The pin 23 rocks the bell-crank 24 to turn the arm25 about its pivot 26. The arm 25 carries a cross piece 27 which bearsupon the arms 5 and 6 and actuates the stylus 7, which, in this case, isnormally out of contact with the chart. The stylus 7 marks a dot uponthe chart, thereby recording its position at the end of the demandinterval.

It is apparent that, from the chart, the average ower factor for anydemand period, and partlcularly for the period of maximum volt-amperedemand, may be obtained. The maximum volt-ampere demand indication will,of course, be the one which is furthest from the initial position of thestylus 7.

It is also apparent that, from a number of installations such as thatdescribed, the comparative maximum demands or average power factor forthe maximum-demand periods may be obtained and, from these quantities,the tariif per kilowatt-hour charged each consumer may bei calculatedupon a graduated scale which takes into account the maximum demand orthe average power factor of the load or both.

By the use of demand meters 35 and 36, of the integrating type, I ensurethat the maximum demand will be within the range of the instrument andwill not be aifected by sudden fluctuations of energy due toshort-circuits or the like. In accordance with my invention all of theforegoing results are accomplished with relatively simple modificationsof standard watthour meters.

I prefer to employ fixed charts that are replaced from time to time but,if desired, they may be movable, as in case of some recording meters.

In the appended claims the term average power factor is to be taken tomean the cosine of the angle whose tangent is the averagereactive-volt-amperes for a given interval of time divided by theaverage active-voltamperes (watts) for that same interval.

I have not attempted to set forth every use to which my invention may beapplled and I do not wish to limit the appende claims because of themention or the omission of certain uses or of mechanical equivalents.

As in my former applicatlon for atent, it will be evident that byintegrating t e power and the reactive components according to time, inthe mechanism illustrated, and then vectorially combining the movements,I am enabled to obtain the results shown, which cannot be accomplishedin an other way with econom and assured resu ts.

In an insta lation which 0 crates for a considerable period, such as oneour, without resetting, the power factor may shift around considerably,and the pointer come over various ones of the lines 18, 19, 20 and 21 onthe chart. The line over which the pointer lies at the end of theinterval of time will give the average power factor, however.

A meter which gives an oscillating indication of a variable powerfactor, on a chart or scale, is of little assistance in giving averagepower factor, since the calculation of average power factor from such anindication is extremely diflicult. In my device, however, the

position of the pointer at any given interval of time with relation tothe lines 18 to 21 on the chart, gives the cosine of the angle betweenthe total'time-integrated movements resulting from the power and fromthe reactive components of the volt-amperes, which is the average powerfactor for that period of time.

I claim as my invention:

1. In combination, achart, a stylus having a definite initial positionand normally out of contact with the chart, means for periodicallydepressing the stylus into contact therewith and then restoring the sameto its initial position, and means for actuating the stylus with respectto the chart in accordance with average power factor demand of anelectrical circuit during the intervals betwieen such depressions.

2. In a metering device, an element'moving as the time-integrated powercomponent of volt-amperes, an element moving as the time-integratedreactive component of voltamperes and means controlled by said twoelements moving over a chart from an initial position and adapted tomark said chart, said chart being calibrated inpower factor linesemanating from the initial position of said marking means to provide anindication of average power factor demand for selected intervals oftime.

integrated power and reactive com nents of volt-amperes in such mannerthat t e position of the marker at the end of any given interval of timewill indicate the average power factor demand for that time.

4. An electrical meter comprising a recordin chart, a pointercooperating therewith, inks connected to said pointer, and

' means for simultaneously driving said links respectively in accordancewith. the integrated watts and the reactive volt-amperes of anelectrical circuit for predetermined equal time intervals, whereby saidpointer marks said recording chart in accordance with the average powerfactor for each time interval.

5. A recording power-factor meter comprising a recording chart, amarking lus cooperating therewith, means for periodically restoring themarking stylus tonormal, and means, including said marking stylus, .forinscrihing upon said chart the values of average powerfactor of anelectrical circuit over a plurality of equal periods of time.

6. A recordlng power-factor meter comprising a recording chart andmeans, includmg link elements driven in accordance with the active andreactive components ofapparent power of an electrical circuit, for

mscribing average-power-factor demand values for predetermined time uponsaid chart. 7. In combination, a chart-marking stylus, integrating meansresponsive to the power and reactive-power components, respectively, ofan electrical circuit and connected to said equal periods of stylus fordriving it in accordance with aver- I age-power-factor demand, and achart ooactin recor mand.

In testimony whereof, I have hereunto subscribed my name this 29th dayof April,

GEORGE SPEBTI.

with said chart-marking stylus 'for period of ng said,average-power-factor de-

